1. Field of the Invention
The present invention relates to a method of manufacturing a coil assembly of a stator of an electric rotating machine.
2. Description of Related Art
There are known various methods of manufacturing a coil assembly of an electric rotating machine. For example, Japanese Patent Application Laid-open No. 2002-176752 discloses a method in which a plurality of coil wires are wound at the same time by use of a pair of opposed plate-like wiring cores. Also, Japanese Patent Application Laid-open No. 2004-104841 discloses a method in which there are repeatedly performed a first step where with respect to one coil wire formed in a triangular wave shape by a winding step, another coil wire is turned by 90 degrees on its axis, and advanced toward the one coil wire to thereby increase their overlapped portions by a half-turn, and a second step where the another coil wire is further turned on its axis, in order that a plurality of coil wires each having a plurality of turn portions are interlaced.
Interlacing a plurality of coil wires each having a plurality of turn portions with one another can be performed also by other methods. Such methods include a method in which around one fixed coil wire, another coil wire is moved by one revolution so that it advances in the coil longitudinal direction by one coil pitch as performed in a typical twinning device, and a method in which two coil wires are held at predetermined angles with respect to their interlacing portions, and are moved around with each other in this state.
However, since these methods use coil wires each having a plurality of turn portions formed by a shaping process, the angle between the axis of one coil wire and the axis of another coil wire has to be set to a large value in order to avoid interference between their turn portions during an interlacing process. This causes a problem that the coil wires (particularly, their linear in-slot portions) deform easily. If the coil wires deform during the interlacing process, the interlaced coil assembly has a warped shape.